Transfer sheet and method of preparing



March 28, 1967 M. s. BARBOUR 3,311,489

TRANSFER SHEET AND METHOD OF PREPARING Filed Sept. 24, 1965 FIG. 1

Transfer cooling Paper base Transfer coating Release coating Paper base .33 Pa per base Transfer coating Paper base lNVENTQR Marshall 8. Barbour ATTORNEYS United States fPatent O 3,311,489 TRANSFER SHEET AND METHQD 9F PREPARING Marshall 5. Barbour, Mexico, Maine, assignor to ()xford Paper Company, Rumford, Maine, a corporation of Maine Filed Sept. 24, 1965, Ser. No. 490,032 13 Claims. (Cl. 117-36. 3)

This application is a continuation-in-part of application Ser. No. 274,71 1, filed Apr. 22, 1963, now abandoned.

This invention relates to transfer sheets such as those commonly known in the art as carbon paper. More particularly, the invention relates to transfer sheets prepared by applying a transfer coating to a flexible foundation, the transfer coating comprising closely packed organic polymer spheres which are bound to each other by a sufiicient amount of a carboxylated polymer to hold the spheres together and to the flexible foundation, but insufficient to hold the transfer coating to the foundation when subjected to local pressure. Polyvalent metal salts are used to insolubilize the carboxylated polymer.

It has been known in the art that transfer sheets can be prepared by applying to a flexible foundation certain coating compositions which are characterized by their having a waxy nature. The ability of these transfer sheets to transfer an image to a receiving surface in response to local pressure is dependent upon the presence of a waxy material in the coating on the sheets. The waxy material is usually composed of mixtures of waxes, oils and oily substances.

The preparation of such wax-type coatings requires special emulsification equipment and the application thereof to a suitable base by the hot-melt type coating equipment which requires slow coating speeds.

The transfer sheets prepared according to this invention avoid many of the disadvantages inherent in the prior art waxy papers. The transfer sheets of this invention are simple and economical to prepare, and they do not involve the preparation of any rigid emulsification of a waxy material or special emulsification equipment. Using conventional coating equipment, high coating speeds can be used in the manufacture of these transfer sheets. The heat limitation factors, such as those which exist when waxy substances are present, are largely avoided. These transfer sheets, moreover, are almost completely dry and smearproof. They possess a high gloss, a high scuff resistance and do not require the presence of a solvent vehicle. These transfer sheets are particularly useful for the reason that they are unusually stable, and after appreciable periods of time, the transfer coating is readily transferred in response to local pressure, such as by a stylus or typewriter key, etc.

In copending application Ser. No. 332,868, there is described a transfer paper comprising a flexible foundation having a transfer coating thereon. The transfer coating contains organic polymer spheres which are bound to each other and to the flexible foundation by a suflicient amount of a carboxylated polymer so as to permit the polymer spheres to be transferred from the flexible foundation to a receiving surface in response to local pressure. The present invention resides in the discovery that the transferability of such coatings can be improved by insolubilizing the carboxylated ploymer with a polyvalent metal 3,3 l 1,489 Patented Mar. 28, 1967 salt. it is well known to those skilled in the art that the use of insolubilizing agents in ordinary paper coating compositions tends to aflix the coating to the paper. But, the use of insolubilizing agents in transferable coating compositions has been avoided because such insolubilizing agents would be expected to afflx the coating and thereby impair the transfer properties of the coating. The insolubilizing agents employed herein are the only ones, of which I am aware, which are capable of insolubilizing the transfer coating composition without interfering with the transfer properties. in fact, I have found that the use of polyvalent metal salts not only produces improved transfer properties initially, but also after aging. The improved transfer properties produced according to the present invention are therefore particularly useful where it is of considerable importance for the transfer paper to maintain its transfer properties after appreciable periods of time.

Although it is known that polyvalent metal salts can be used to insolubilize carboxylated polymers which are present in permanently affixed paper coatings, and although such insolubilization is effective in decreasing the moisture susceptibility of said coatings, the use of insolubilizing agents in transfer coatings has been avoided in the past, as pointed out above, because of the expected loss in transfer properties. Such loss in the transfer properties could not be permitted even though there may be advantages derived from a decrease in the moisture susceptibility of the coating.

The transfer coating of this invention consists of closely packed organic polymer spheres, particularly polystyrene spheres, bonded together and to a flexible foundation, such as paper, with an amount of carboxylated polymer sufficient to resist ordinary scuff and bending during normal handling, but in an amount less than that which would prevent release of the coating from the paper stock when subjected to local pressure. Polyvalent metal salts are employed for the purpose of insolubilizing the carboxylated polymer. The transfer coating may advantageous ly contain at least about of polystyrene and advantageously no more than about 8% by weight of the carboxylated polymer. The transfer sheets of this invention may be prepared by mixing together an aqueous suspension of polystyrene, one or more polyvalent metal salts, coloring matter, such as a pigment or dye, and a carboxylated polymer, and then applying the coating to a flexible foundation and drying the coating thereon.

The polystyrene particles, which are in discrete, particulate form, and which advantageously comprise at least about 70% by weight of the transfer coating, closely approximate a system of closely packed spheres. These spheres have substantially no tendency to coalesce, that is, to deform from their essentially spherical geometry under manufacturing and in-use conditions. Therefore, the temperature used during the manufacturing operation and the time period during which this temperature is maintained is such that the polystyrene spheres maintain their hard glassy properties and do not tend to coalesce. The use of these polystyrene spheres form a stable coating of close-packed, uncoalesced, hard, glassy spherical particles upon their application, as an aqueous emulsion, to the base stock followed by a rapid water removal operation.

A system of close-packed, spherical particles, such as obtained by rapid drying of a polystyrene emulsion film, contains up to about 27% void volume. At a typical coatweight of 3.3# per ream, a film employing a polystyrene emulsion (manufactured by the Monsanto Chemical Company, under the trade name Lytron S2) is about '7 microns thick after water removal, corresponding to about layers of close-packed polystyrene particles. It is advantageous to this invention that the average particle size of the polystyrene particles be such that the individual voids created as a result of spherical close-packing can easily contain colored pigment particles. For example, use of polystyrene in conjunction with a copper phthalocyanine pigment dispersion, allows formation of a coating such that about 30 copper phthalocyanine pigment particles can be packed in each void formed among the hard polystyrene particles.

The polystyrene spheres employed in this invention are prepared by forming an aqueous emulsion of polystyrene, wherein the particle size of the individual polymer spheres is advantageously from about 0.05 to 0.3 micron. Any suitable polystyrene emulsion can be used, including the polystyrene emulsions marketed by Monsanto Chemical Company under the trade names Lytron S-1, and Lytron 8-2 (having polymer sizes of about 0.16 and 0.23 micron respectively), polystyrene latex of Dow Chemical Company (Dow Latex 586), and the like.

Although polystyrene spheres are preferred, other organic polymer spheres may be employed, such as those described in copending application Ser. No. 332,868. For example, the organic polymer spheres may be prepared by forming an aqueous emulsion of a resinous material having a glass transition temperature sufficiently high so that the polymer spheres are not substantially deformed or coalesced at the temperatures at which the transfer sheets are prepared and stored. These polymers include the socalled non-film forming thermoplastic resin-s as well as thermosetting resins. Although it is difficult at times to define a definite borderline between thermosetting resins and thermoplastic resins, the important point is that the resins should be non-film forming at application and dry ing temperatures and should be capable of being mixed in an aqueous medium with an adhesive and then applied to a suitable base sheet and then dried to form a coating containing loosely bound pigment-like resin particles, this coating being capable of being transferred to a receiving surface in response to local pressure. These polymers are used in emulsion form, and water is the preferred medium in which the polymers are dispersed. It is believed that other mediums could be employed so long as the essential relationship between the polymer spheres and the adhesive is maintained.

Various non-film forming resins can be used according to this invention, including polystyrene, as described above, polyacryiic resins such as those marketed by Rohm & Haas under the trade name Rhoplex B-SS, polyvinyl chloride such as marketed by the Monsanto Chemical Company under the trade name Opalon 410, polyvinyl chloride latex such as marketed by the Dow Chemical Company under the trade name Dow Latex 700, vinyl chloride-vinylidene chloride copolymer latex such as marketed by the Dow Chemical Company under the trade nan e Dow Latex 744-3, and the like. Other systems of spherical particles, of course, can be used along with, or in place of, the organic polymer spheres described above, so long as these spherical particles function in substantially the same way as those prepared from the organic polymer emulsions. It is preferred that these spherical particles have an average diameter of about 0.05 to 0.3 micron. Depending upon the particular ingredients used and the degree of transferability desired, this range can, of course, vary. Larger polymer particles, for example, will tend to transfer more readily than smaller particles.

The transfer properties of the transfer sheets of this invention, as operational products, are directly related to the strength of the adhesive bonds between the polystyrene spheres and to the adhesion of the coating to the paper. In order to obtain clear, sharply-defined, transferred images, the carboxylated polymer need only bind the polystyrene spheres together in the vicinity of the contact points resulting from their close-packing. Adhesive contents beyond this are conducive to a less sensitive transfer and adhesive levels below this lead to a powdery, ill-defined image, lacking desirable handling properties of the coated sheet.

The carboxylated organic polymers, that is, those which possess periodic carboxylic acid groups along the polymer chain, such as ca-rboxymethyl cellulose, polyacrylic acid and copolymers of acrylic acid, sodium polyacrylate, and other aqueous solutions of polymeric acrylic salts, as well as emulsions, which are marketed by Rohm & Haas under the trade name Acrysol ASE 60, ASE and ASE 95, for example, and the like, are used as the adhesive and serve as a flexible adhesive that provides a very desirable quality of binding of the polystyrene spheres to each other and to the flexible foundation.

These carboxylated polymers are advantageously used in the range of about 0.8-8% by weight of the coating, and preferably 1-5% by weight. Higher amounts may be used but are generally unnecessary. Any moisture susceptibility of the dried coating is advantageously decreased by including in the coating formulation suitable polyv-alent salts in approximately stoichiometric quantities which react with the carboxylic acid groups to form insoluble polyvalent metal salts of the carboxylated polymer during the drying step. It is believed that the carboxyl groups of the carboxylated polymers inter-act in some favorable way with the coloring matter, i.e., colored pigment particles, and also with the polystyrene so as to produce a transfer coating having superior transfer characteristics which remain substantially unchanged over appreciable periods of time.

The polyvalent salts which may be used include zinc ammonium acetate, zinc phenol sulfonate, zinc sulfamate, zinc silicofiuoride, zinc chloride, alum, as well as salts of other divalent and trivalent metals, e.g., lead, calcium, manganese, cerium, lanthanum, and the like.

Any suitable dye or coloring matter, i.e., colored pigment particles, may be mixed in with the coated composition. Examples of such dyes which have been advantageously employed include phthalocyanine pigment dye such as phthalocyanine blue marketed by American Cyanamid under the trade name Calcot'one Blue G. Paste, and carbon black, such as that manufactured under the trade name Aquablak B by Columbia Carbon Company.

Various compatible plasticizers may be incorporated into the coating composition in small amounts as hereinafter described, such as butyl benzyl phthalate, manufactured under the trade name Santicizer 160 as well as other well-known plasticizers which will be apparent to those skilled in the art.

The plasticizer which may be used should only be present in small amounts. The ratio of resin to plasticizer is advantageously about 1.25. This ratio can, however, go as high as about 100:5. The use of plasticizers in excessive amounts will substantially interfere with the transfer properties of the transfer sheets and must be avoided.

In addition to the polystyrene, carboxylated polymer, and coloring matter, various additives may be used to improve the handling characteristics or release characteristics. Such additives include calcium stearate, potassium stearate, ammonium stearate, polyoxyethylene glycols, lecithin, polybutenes, polyethylene emulsions, or soft waxes. The only requirement is that these additives, together with the adhesive and coloring matter, should not completely fill the voids between the polystyrene spheres, i.e., the polystyrene spheres should comprise at least about 70% by weight of the transfer coating.

The temperature at which the coating composition is blended together, of course, depends upon the particular components employed. A temperature of about 60 F. to 100 F. may be advantageously employed in most instances. In drying the coating, it is desirable to supply a suitable degree of heat in order to speed up the drying process. The only requirement as to this temperature is that it should not be sufficient to significantly soften the polystyrene spheres and destroy the particle nature of the polystyrene which would interfere with the transfer properties desired in the resulting sheet. In non-plasticized polystyrene formulations, for example, dryer temperatures should be less than about 212 F. Somewhat lower temperatures should generally be used with plasticized polystyrene since the softening point of the plasticized polystyrene is generally lower than that of the non-plasticized polystyrene. The specific drying temperature used with any particular formulation man be determined by routine experimentation by those skilled in the art. If forced hot-air drying procedures are used, up to 250 F, ambient temperature, at web speeds such that water evaporation takes place within 5 to seconds dwelltirne, may be used. Under these conditions the coated web temperature rarely rises above 140 F.

The limitation on the drying temperature is quite ad vantageous and one aspect of the invention includes the step of heating of the transfer coatings to temperatures above the softening point of the polystyrene spheres so as to deactivate or destroy the transfer properties of the film. The fact that the transfer properties of the film can be destroyed by the simple expedient of heat, permits the transfer coatings to be rendered non-transferable after the transfer coating has served its purpose, and results in an original record (typewritten, for example) having a non-transferable coating 'on the back. In addition, the image transferred to a receptor paper can also be deactivated by heating the transferred image, thus improving the smudgeproofness and permanence of the transferred image.

The coating may be applied to any suitable backing material, usually paper. A coating applied at a coating weight of about 2 to 4 lbs. per ream x 38"500 (sheets) is desirable. This weight, however, could vary from about l-to 7 lbs. per ream. The coating may be applied at any suitable solids content, generally ranging from about 10 to 40%. On an airknife coater, optimum results were obtained on a solids content in excess of The coating may be applied at a machine speed ranging from about 100 to 500 ft. per minute. Even higher machine speeds would probably be suitable.

The receiving surface, which accepts the transferred image from the transfer sheets of this invention, is a surface which advantageously has been treated with a receptor coating. A specially treated paper, having a receptor coating, which can be used, is one which is coated with a composition containing, for example, a liquid dispersion of calcium carbonate having a relative sedimentation volume of between about 2 and 6 in admixture with an adhesive, the composition having a pigment/ adhesive ratio of about between 7:1 and 2:1. Such a specially treated receptive paper is described more particularly in the copending application of William H. Hoge and Marshall S. Barbour, Ser. No. 79,980, filed Ian. 3, 1961, assigned to the same assignee as the present application.

Thus one aspect of this invention includes the use of a combination of two coated papers, the transfer paper overlaying a-receptor paper, wherein the transfer coating of the transfer paper is in contact with the receptor coatingzof the receptor paper. Local pressure applied to the transfer paper therefore results in a transferred image 'on the receptor paper corresponding in area to the area at which the local pressure was applied to the transfer paper. Alternatively, a transfer coating can be applied to one side of a paper and a receptor coating applied to the other side and then two or more of these sheets can be placed together so that the transfer coating of one sheet is in contact with the receptor coating of another sheet.

The transfer sheets of this invention can also be used in conjunction with ordinary copy paper for reception of the image to be transferred.

A release coating between the paper base and the transfer coating can be used in this invention is desired. Such a release coating can advantageously be used to facilitate transfer of the transfer coating to ordinary copy papers or papers not having an image receptive coating applied thereto.

Various release coatings can be used according to this invention such as those composed predominantly of vinyl resins. Cellulosic, polyamide, acrylic or methacrylic resins and so forth can also be used. Further examples of release coatings include cellulosic resins such as hydroxyethyl cellulose polyamide, acrylic or methacrylic resins as well as inorganic materials such as sodium silicate or colloidal silica (e.g., silica manufactured by Monsanto Chemical Company under the trade name Syton). The release coating can be applied by solvent or water techniques as will be apparent to those skilled in the art. Specific examples of release coatings include 20 parts by weight vinylidene chloride, vinyl chloride copolymer dissolved in parts by weight methylethyl ketone, 5 parts by weight polyvinyl butyral dissolved in 80 parts by weight ethanol and 6 parts by weight of a silica filler.

In the following detailed examples, which are given for illustrative purposes only, specific embodiments of this invention are shown, and in FIGS. 13 of the accompanying drawing, three typical embodiments of the transfer sheets of this invention are shown diagrammatically in cross-section.

FIG. 1 shows a paper base 10 having a transfer coating 11 prepared according to the present invention adhered to the paper base. FIG. 2 shows a paper base 20 with a release coating 21 adhered thereto and the transfer coating 22 prepared according to this invention adhered to the release coating. FIG. 3 shows a combination of a paper base 30 having a receptor coating 31 adhered thereto and the receptor coating contacting the transfer coating 32 prepared according to this invention adhered to the paper base 33. The application of pressure by means of a stylus or typewriter key on the top or uncoated side of paper base 33 results in a transfer of the transfer coating to the receptor coating on paper base 30 in areas coextensive with the application of the pressure.

In the following examples parts are by weight.

Example 1 62.4 parts of an aqueous emulsion of polystyrene containing 40% solids (Lytron 8-1) were thoroughly mixed together with 1.5 parts of an acrylic emulsion copolymer (40% solids) which is water soluble in alkaline solutions, (Acrysol ASE 75), 45 parts of a 2% solution of phthalocyanine blue, 0.25 part of a 28% ammonia solution, 11.5 parts water, and 0.6 part of zinc ammonium acetate (prepared from 4 parts of zinc acetate dihydrate and 4.4 parts of a 28% solution of ammonia). The coating composition thus prepared was then applied on to a base paper at a coat Weight of 3 pounds per ream and the coating dried at a temperature of F. The dry transfer coating possessed a high gloss, high scuff resistance and was substantially smudgeproof. The coating on the base paper was then placed in contact with a sheet of conventional bond white paper and pressure applied by means of a stylus to the backside of the paper having the transfer coating applied thereto. The coating readily transferred to the bond paper receiving surface underlying the coating in the areas coextensive with the applied pressure. The image transferred to the bond receiving surface was sharp and distinct, possessed a high scuff resistance, was substantially smudgeproof and dry.

The coated paper, to which the stylus had been applied, was heated to a temperature above the softening point of the polystyrene particles contained therein for a sufficient time to substantially eliminate the particle nature of the non-film forming polystyrene pigment particles. This heating step rendered the coating non-transferable. The bond paper, having the transferred image thereon, was heated to a temperature above the softening point of the polystyrene particles in the same manner as the sheet having the transfer coating thereon. The image was completely smudgeproof and dry and possessed a high degree of permanence.

The coated surface of another portion of the transfer sheet prepared according to this example was placed against a sheet of paper having a receptive coating thereon prepared according to Example 1 in application Ser. No. 79,980. When pressure was applied by means of a stylus to the backside of the paper having transfer coatings adhered thereto, the coating transferred even more readily to give an extremely clear and sharp image on the receptive coating of the underlying sheet.

Example 2 A transfer sheet was prepared in the same manner as set forth in Example 1, except that the transfer coating composition was formed by thoroughly mixing together 62.4 parts of an aqueous emulsion of polystyrene containing 40% solids (Lytron 5-1), 2 parts of an acrylic emulsion copolymer (40% soiids) which is water soluble in alkaline solutions (Acrysol ASE 75), 7 parts of a 20% solution of phthalocyanine blue, 0.7 part of zinc ammonium acetate, 0.3 part of a 28% ammonia solution, 52 parts water, 1.8 parts of 50% suspension of calcium stearate (lubricant), and 1 part of sodium chloride (viscosity reducing agent).

The transfer sheet prepared according to Example 2 was observed and tested in the same manner as set forth in Example 1. The dry transfer coatings possessed a high gloss, high scuff resistance and were substantially smudgepr-oof and possessed substantially the same transfer and deactivation properties as described with respect to the transfer sheet prepared in Example 1.

In the above examples it was noted that there was a proper amount of adhesive present in the coating compositions, i.e., there was a sufficient amount of adhesive to hold the resin particles together and adhere the coating to the paper, but the amount of adhesive was insufficient to hold the coatings to the paper when subjected to the pressure such as from a stylus or a typewriter key under normal operation conditions.

The transfer sheets prepared according to Examples 1 and 2 maintained their good transfer properties after several months of storage.

Iclairn:

1. A transfer sheet comprising a flexible foundation and a coating adhered thereto, said coating comprising discrete, non-coalesced organic polymer spheres having a glass transition temperature of at least about 140 F. and having a particle size between about 0.05 and 0.3 micron, coloring matter, and a polyvalent metal salt of a carboxylated polymer which is in an amount sufficient to hold the organic polymer spheres together and to the flexible foundation, but insufiicient' to hold the organic polymer spheres to the flexible foundation when subjected to local pressure, said coating being in an amount equivalent to the amount of coating on a coated paper having from 1 to 7 lbs. of coating per ream of paper, and said coloring matter, together with the polyvalent metal salt of a carboxylated polymer being in an amount which is insufficient to completely fill the voids which exist between the organic polymer spheres.

2. A transfer sheet comprising a flexible foundation and a coating adhered thereto, said coating comprising discrete, non-coalesced polystyrene spheres having a particle size between about 0.05 and 0.3 micron, coloring matter, and a polyvalent metal salt of a carboxylated polymer which is in an amount sufficient to hold the polystyrene spheres together and to the flexible foundation, but insufiicient to hold the polystyrene spheres to the flexible foundation when subjected to local pressure, said coating being in an amount equivalent to the amount of coating on a coated paper having from 1 to 7 lbs. of coating per ream of paper, and said coloring matter, together with the polyvalent metal salt of a carboxylated polymer being in an amount which is insutiicient to completely fill the voids which exist between the polystyrene spheres.

3. The transfer sheet of claim 1 in which the organic polymer spheres comprise at least about by weight of the coating, the polyvalent metal salt of the carboxylated polymer comprises no more than about 8% by weight of the coating, the flexible foundation is paper, and the coating is at a coat weight of about 2-4 lbs. per ream of paper.

4. The transfer sheet of claim 2 in which the polyvalent metal salt of the carboxylated polymer is the reaction product of a polyvalent metal salt with a water soluble salt of an acrylic polymer containing carboxyl groups.

5. The transfer sheet of claim 2 in which a plasticizer is present in an amount of from about 15% by weight.

6. The transfer sheet of claim 2 in which a release coating is adhered between the backing and the transfer sheet.

7. The method of preparing a transfer sheet which comprises coating a suitable base sheet with a coating composition comprising an aqueous emulsion of an organic polymer having a glass transition temperature of at least about F. and having a particle size between about 0.05 and 0.3 micron in admixture with a car'- boxylated polymer, at least one po-lyvalent metal salt, and coloring matter, heating the coating to a temperature which will not substantially deform the organic polymer spheres, but which will dry the coating composition on the base sheet, said coating being present on the base sheet in amount which is equivalent to a coat weight of about 1 to 7 lbs. of coating per ream of paper.

8. The method of preparing a transfer sheet which comprises coating a suitable base sheet with a coating composition comprisin an aqueous emulsion of polystyrene spheres having a particie size between about 0.05 and 0.3 micron in admixture with a carboxylated polymer, at least one polyvalent metal salt, and coloring matter, heating the coating to a temperature which will not substantially deform the polystyrene spheres, but which will dry the coating composition on the base sheet, said coating being present on the base sheet in an amount which is equivalent to a coat weight of about 1 to 7 lbs. of coating per ream of paper.

9. The method of claim 8 comprising the additional step of applying a release coating to the base sheet and coating the transfer coating composition on the release coating.

10. The method of claim 8 in which the coating contains at least about 70% by weight of polystyrene.

11. The method of claim 9 in which the base sheet is paper. 1 2. The method of claim 11 in which the coat weight is 2 to 4 lbs. per ream.

13. The method of preparing a transfer sheet which comprises coating a suitable base sheet with a-release coating, then forming on the release coating a transfer coating comprising discrete, non-coalesced polystyrene spheres having a particle size between about 0.05 and 0.3 micron, coloring matter, and a polyvalent metal salt of a carboxylated polymer which is in an amount sufficient to hold the poiystyrene spheres together and to the flexible foundation, but insufiicient to hold the polystyrene spheres to the flexible foundation when subjected to local pressure, said coating being in an amount equivalent to the amount of coating on a coated paper having from 1 to 7 lbs. of coating per ream of paper, and said coloring matter, together with .the polyvalent metal salt of a carboxylated polymer being in an amount which is insufficient to completely fill the voids which exist between the polystyrene spheres.

(References on foliowing page) References Cited by the Examiner UNITED STATES PATENTS Statham 117-156 Rafsky 117-156 5 Hughes et a1 106-148 Clark 106-148 Seymour 260-455 Newman 117-367 Newman 117-622 Azorlosa 117-622 Newman et a1. 117-361 Newman et a1 11736.1 Popielski.

Gumbinner 117-361 Newman 106-145 MURRAY KATZ, Primary Examiner. 

1. A TRANSFER SHEET COMPRISING A FLEXIBLE FOUNDATION AND A COATING ADHERED THERETO, SAID COATING COMPRISING DISCRETE, NON-COALESCED ORGANIC POLYMER SPHERES HAVING A GLASS TRANSITION TEMPERATURE OF AT LEAST ABOUT 140*F. AND HAVING A PARTICLE SIZE BETWEEN ABOUT 0.05 AND 0.3 MICRON, COLORING MATTER, AND A POLYVALENT METAL SALT OF A CARBOXYLATED POLYMER WHICH IS IN AN AMOUNT SUFFICIENT TO HOLD THE ORGANIC POLYMER SPHERES TOGETHER AND TO THE FLEXIBLE FOUNDATION, BUT INSUFFICIENT TO HOLD THE ORGANIC POLYMER SPHERES TO THE FLEXIBLE FOUNDATION WHEN SUBJECTED TO LOCAL PRESSURE, SAID COATING BEING IN AN AMOUNT EQUIVALENT TO THE AMOUNT OF COATING ON A COATED PAPER HAVING FROM 1 TO 7 LBS. OF COATING PER REAM OF PAPER, AND SAID COLORING MATTER, TOGETHER WITH THE POLYVALENT METAL SALT OF A CARBOXYLATED POLYMER BEING IN AN AMOUNT WHICH IS INSUFFICIENT TO COMPLETELY FILL THE VOIDS WHICH EXIST BETWEEN THE ORGANIC POLYMER SPHERES. 